Add a si_string function to string_utils.

Make the add-on manager and screenshot hotkey use it.

src/addon/manager.cpp

@@ -408,34 +408,8 @@ namespace {
 	 */
 	static std::string format_file_size(double size)
 	{
-		const double k = 1024;
 		if(size > 0.0) {
-			std::string size_postfix = _("B");	// bytes
-			if(size > k) {
-				size /= k;
-				size_postfix = _("KB");			// kilobytes
-				if(size > k) {
-					size /= k;
-					size_postfix = _("MB");		// megabytes
-					if(size > k) {
-						size /= k;
-						size_postfix = _("GB");	// gigabytes
-					}
-				}
-			}
-
-			std::ostringstream stream;
-#ifdef _MSC_VER
-			// Visual C++ makes 'precision' set the number of decimal places.
-			// Other platforms make it set the number of significant figures
-			stream.precision(1);
-			stream << std::fixed << size << size_postfix;
-#else
-			if (size < 100) stream.precision(3);
-			else size = trunc(size);
-			stream << size << size_postfix;
-#endif
-			return stream.str();
+			return utils::si_string(size);
 		} else {
 			return "";
 		}

src/hotkeys.cpp

@@ -1179,7 +1179,7 @@ void execute_command(display& disp, HOTKEY_COMMAND command, command_executor* ex
 			int size = disp.screenshot(filename, map_screenshot);
 			if (size > 0) {
 				std::stringstream res;
-				res << filename << " ( " << size/1000000 <<" "<< (size/1000)%1000 << " kB )";
+				res << filename << " ( " << utils::si_string(size, true, "B") << " )";
 				gui2::show_message(disp.video(), _("Screenshot done"), res.str());
 			} else
 				gui2::show_message(disp.video(), _("Screenshot done"), "");

src/serialization/string_utils.cpp

@@ -26,6 +26,7 @@
 #include "log.hpp"
 #include "serialization/string_utils.hpp"
 #include "../util.hpp"
+#include <boost/array.hpp>
 
 static lg::log_domain log_engine("engine");
 #define ERR_GENERAL LOG_STREAM(err, lg::general)
@@ -259,6 +260,82 @@ std::string signed_value(int val)
 	return oss.str();
 }
 
+template <typename T>
+void si_string_impl_stream_write(std::stringstream &ss, T input) {
+#ifdef _MSC_VER
+	// Visual C++ makes 'precision' set the number of decimal places.
+	// Other platforms make it set the number of significant figures
+	ss.precision(1);
+	ss << std::fixed
+	   << input;
+#else
+	ss.precision(3);
+	ss << input;
+#endif
+}
+template <> void si_string_impl_stream_write(std::stringstream &ss, int input) {
+	ss << input;
+}
+template <> void si_string_impl_stream_write(std::stringstream &ss, long input) {
+	ss << input;
+}
+template <> void si_string_impl_stream_write(std::stringstream &ss, long long input) {
+	ss << input;
+}
+template <typename T>
+std::string si_string_impl(T input, bool base2, std::string unit) {
+	const int multiplier = base2 ? 1024 : 1000;
+	// (input == -input) can happen if we're at the minimum of the native signed integer type, so make sure we don't recurse infinitely
+	// It will still give bad output, but it won't overflow the stack
+	if (input < 0 && input != -input)
+		return unicode_minus + si_string(-input, base2, unit);
+
+	typedef boost::array<std::string, 9> strings9;
+
+	strings9 prefixes;
+	strings9::const_iterator prefix;
+	if (input < 1.0) {
+		strings9 tmp = { { "", "m", "μ", "n", "p", "f", "a", "z", "y" } };
+		prefixes = tmp;
+		prefix = prefixes.begin();
+		while (input < 1.0  && *prefix != prefixes.back()) {
+			input *= multiplier;
+			++prefix;
+		}
+	} else {
+		strings9 tmp = { { "", "k", "M", "G", "T", "P", "E", "Z", "Y" } };
+		prefixes = tmp;
+		prefix = prefixes.begin();
+		while (input > multiplier && *prefix != prefixes.back()) {
+			input /= multiplier;
+			++prefix;
+		}
+	}
+
+	std::stringstream ss;
+	si_string_impl_stream_write(ss, input);
+	ss << ' '
+	   << *prefix
+	   << (base2 ? "i" : "")
+	   << unit;
+	return ss.str();
+}
+std::string si_string(double input, bool base2, std::string unit) {
+	return si_string_impl(input, base2, unit);
+}
+std::string si_string(int input, bool base2, std::string unit) {
+	return si_string_impl(input, base2, unit);
+}
+std::string si_string(long input, bool base2, std::string unit) {
+	return si_string_impl(input, base2, unit);
+}
+std::string si_string(long long input, bool base2, std::string unit) {
+	return si_string_impl(input, base2, unit);
+}
+std::string si_string(long double input, bool base2, std::string unit) {
+	return si_string_impl(input, base2, unit);
+}
+
 static bool is_username_char(char c) {
 	return ((c == '_') || (c == '-'));
 }

src/serialization/string_utils.hpp

@@ -138,6 +138,14 @@ std::string signed_value(int val);
 /** Convert into a percentage (using the Unicode "−" and +0% convention */
 inline std::string signed_percent(int val) {return signed_value(val) + "%";}
 
+/** Convert into a string with an SI-postfix */
+std::string si_string(double input, bool base2=true, std::string unit="B");
+std::string si_string(int input, bool base2=true, std::string unit="B");
+/* Some extra-long versions */
+std::string si_string(long input, bool base2=true, std::string unit="B");
+std::string si_string(long long input, bool base2=true, std::string unit="B");
+std::string si_string(long double input, bool base2=true, std::string unit="B");
+
 /**
  * Try to complete the last word of 'text' with the 'wordlist'.
  *